Getting and adding comments to/from a VSO Git pull request using the VSO Rest API

I'm trying to use the VSO rest apis to view and edit Git pull requests. So far I've been able to figure most things out, like the following:

 1) Getting pull request info

 2) Getting the actual source and destination file contents

 3) Adding and removing users from the pull request

But the one thing I can't figure out is actually getting and adding comments to/from the pull request.  Is this possible using the VSO rest API?  If not, is there another way to accomplish this?

Thanks in advance,

Luke